Much of contemporary social life occurs in "cyberspace." People increasingly conduct business, make friends, and fall in love over e-mail. There is a growing consensus that computers are changing the way people communicate with each other, but to what extent is computer- mediated social interaction really different from face-to-face interaction? The medium through which people communicate has profound effects on the availability, meaning, and frequency of a wide range of linguistic, paralinguistic, and nonverbal cues, including proxemics, posture, gaze, facial expression, gesture, and touch. These cues have well-documented links to interpersonal variables, such as dominance, affiliation, trust, deception, and affective responses. Thus, there are good reasons to expect that the medium of communication will influence interpersonal perceptions and behaviors. To date, however, there has been far more speculation than data about the effects of communication medium on social interaction. The purpose of the proposed research is to conduct a series of controlled studies examining how various interpersonal processes are affected by the medium of communication. The basic design of these studies will entail the replication across media of a naturalistic interaction ("getting acquainted") that occurs frequently in everyday life and has an established body of findings in the psychological literature. A strength of the research is that we will sample three points along the continuum of what Daft and Lengel (1986) refer to as medium "richness," that is, the number and type of communication channels available. Thus, we will contrast data from a baseline (face-to-face) condition with two less rich conditions, phone and computer-mediated. In all three conditions, participants will provide ratings of their own and their partner's behavior; in addition, the conversations will be coded by independent observers and by a computerized content coding program. Analyses will focus on how communication medium affects three basic aspects of interpersonal interaction: social behavior and its perception, causal attribution, and interpersonal attraction. The findings emerging from this research will help us to understand the psychological effects of an increasingly ubiquitous mode of communication. while also providing a new way to address longstanding theoretical questions about the impression formation process.